package io.github.dunwu.springboot.snake;

import org.springframework.web.socket.TextMessage;
import org.springframework.web.socket.WebSocketSession;

import java.util.ArrayDeque;
import java.util.Collection;
import java.util.Deque;

public class Snake {

    private static final int DEFAULT_LENGTH = 5;

    private final Deque<Location> tail = new ArrayDeque<>();

    private final Object monitor = new Object();

    private final int id;

    private final WebSocketSession session;

    private final String hexColor;

    private Direction direction;

    private int length = DEFAULT_LENGTH;

    private Location head;

    public Snake(int id, WebSocketSession session) {
        this.id = id;
        this.session = session;
        this.hexColor = SnakeUtils.getRandomHexColor();
        resetState();
    }

    private void resetState() {
        this.direction = Direction.NONE;
        this.head = SnakeUtils.getRandomLocation();
        this.tail.clear();
        this.length = DEFAULT_LENGTH;
    }

    public void update(Collection<Snake> snakes) throws Exception {
        synchronized (this.monitor) {
            Location nextLocation = this.head.getAdjacentLocation(this.direction);
            if (nextLocation.x >= SnakeUtils.PLAYFIELD_WIDTH) {
                nextLocation.x = 0;
            }
            if (nextLocation.y >= SnakeUtils.PLAYFIELD_HEIGHT) {
                nextLocation.y = 0;
            }
            if (nextLocation.x < 0) {
                nextLocation.x = SnakeUtils.PLAYFIELD_WIDTH;
            }
            if (nextLocation.y < 0) {
                nextLocation.y = SnakeUtils.PLAYFIELD_HEIGHT;
            }
            if (this.direction != Direction.NONE) {
                this.tail.addFirst(this.head);
                if (this.tail.size() > this.length) {
                    this.tail.removeLast();
                }
                this.head = nextLocation;
            }

            handleCollisions(snakes);
        }
    }

    private void handleCollisions(Collection<Snake> snakes) throws Exception {
        for (Snake snake : snakes) {
            boolean headCollision = this.id != snake.id && snake.getHead().equals(this.head);
            boolean tailCollision = snake.getTail().contains(this.head);
            if (headCollision || tailCollision) {
                kill();
                if (this.id != snake.id) {
                    snake.reward();
                }
            }
        }
    }

    public Location getHead() {
        synchronized (this.monitor) {
            return this.head;
        }
    }

    public Collection<Location> getTail() {
        synchronized (this.monitor) {
            return this.tail;
        }
    }

    private void kill() throws Exception {
        synchronized (this.monitor) {
            resetState();
            sendMessage("{'type': 'dead'}");
        }
    }

    protected void sendMessage(String msg) throws Exception {
        this.session.sendMessage(new TextMessage(msg));
    }

    private void reward() throws Exception {
        synchronized (this.monitor) {
            this.length++;
            sendMessage("{'type': 'kill'}");
        }
    }

    public String getLocationsJson() {
        synchronized (this.monitor) {
            StringBuilder sb = new StringBuilder();
            sb.append(String.format("{x: %d, y: %d}", Integer.valueOf(this.head.x), Integer.valueOf(this.head.y)));
            for (Location location : this.tail) {
                sb.append(',');
                sb.append(String.format("{x: %d, y: %d}", Integer.valueOf(location.x), Integer.valueOf(location.y)));
            }
            return String.format("{'id':%d,'body':[%s]}", Integer.valueOf(this.id), sb.toString());
        }
    }

    public int getId() {
        return this.id;
    }

    public String getHexColor() {
        return this.hexColor;
    }

    public void setDirection(Direction direction) {
        synchronized (this.monitor) {
            this.direction = direction;
        }
    }

}
